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The Environment at Westminster Hills

 

The Guardians are just as passionate about sustainability and responsible land management as we are about our four-legged friends! We feel strongly that we have a duty to preserve this treasured resource for generations to come.

What is the short grass prairie?

The shortgrass prairie is predominantly made up of blue grama and buffalo grass as well as other diverse species of grasses, forbs, shrubs, and wildflowers. The shortgrass prairie is home to many animals including songbirds, raptors, reptiles, and mammals such as prairie dogs.

Much of the land in eastern Colorado used to host a thriving shortgrass prairie ecosystem before the Denver metro area sprawled across the landscape, and millions of acres were lost to agriculture and urban development. Both the intentional and unintentional introduction of nonnative grasses, invasive plant species, and noxious weeds has further altered the landscape of this critical ecosystem. Herds of bison, pronghorn, deer, and elk that once roamed the great expanse of grassland have largely been replaced by grazing cattle. Predators such as the gray wolf, grizzly bears, and the black footed ferret have long since disappeared and been replaced by coyotes.

The Colorado State Wildlife Action Plan shows that there are nearly 12 million acres of shortgrass prairie in Colorado. Conservation efforts to protect what remains of the shortgrass prairie are laid out in the Conservation Plan for Grassland Species and are primarily focused on the millions of acres of shortgrass prairie in eastern Colorado, particularly the USDA National Grasslands and privately-owned grasslands.

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The Shortgrass Prairie at Westminster Hills

The Westminster Hills Open Space and Off-Leash Dog Park (WHOS) consists of 1,027 acres of rolling hills and open lands purchased with funds from the Open Space Program. The citizens of Westminster were instrumental in obtaining access to the land for use as an off-leash dog park as early as 1999. The current 420 acre off-leash access has been in place since 2009.

As an ecosystem, the WHOS property is partially fragmented as it is bordered by housing developments and an airport. On the western boundary, WHOS connects across Indiana Street to tens of thousands of acres of grassland in Rocky Flats and Boulder Open Spaces. Habitat management along the Front Range poses several challenges due to fragmentation and increasing urban growth, and the remaining shortgrass prairie in the WHOS has limited ability to support a fully intact prairie ecosystem. Despite this, the shortgrass prairie at WHOS provides a refuge for wildlife in the urban environment as well as provides educational and wildlife viewing opportunities for the community.

The land at WHOS has historically been used for agricultural purposes, including cattle grazing. Cattle were regularly seen on portions of the WHOS acreage until 2010, which has left lasting impacts to the land. Even more impact was incurred from the relocation of prairie dog colonies into WHOS over the early 2000s. The high density of prairie dogs greatly altered the natural landscape, decimating native vegetation, creating baren land which contributed to the spread of invasive plants and noxious weeds that were able to take root and outcompete native grasses. The two photos below show the impact of prairie dog relocation and are included in Westminster’s Wildlife and Natural Resource Management Plan:

WHOS Over Time

In the 2014 Open Space Stewardship Plan, WHOS was designated as a priority area requiring a master management plan. As part of this process, Westminster Parks, Recreation, and Libraries (PRL) hired ERO Resources Corporation, an environmental consultant headquartered in Denver, to complete an environmental assessment of the land in the summer of 2023. The report was published in January 2024; read it HERE or at the link below.

See also the Guardian’s press release regarding City staff direction given to the third-party ERO to alter initial findings presented in the conditions report. Although disappointed to learn that the independent environmental assessment had been altered to align with PRL intent to reduce the dog park, the Guardians believe the ERO report to nonetheless provide critical information regarding plant and animal species living in the park and that this information remains accurate and independent of City staff input.

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Vegetation

Most of the WHOS is grassland. ERO assessed the vegetation at WHOS and estimated there to be approximately 450 acres of mixed grassland, 303 acres of nonnative grassland, and 220 acres of areas dominated by noxious weeds. Smaller vegetation type areas were identified as 1.3 acres of riparian woodland and 3.9 acres of emergent marsh wetland near the Mower Reservoir in the western portion of WHOS. The map below depicts the dominant vegetation types.

ERO Vegetation

ERO found that the vegetation was dominated by the nonnative grassland species smooth brome. Other noxious weeds and native species found included: prairie sagewort, kochia, cheatgrass, musk thistle, field bindweed, redstem fillaree, dalmatian toadflax, alfalfa, western wheatgrass, scarlet globemallow, common mullein, and soapweed yucca.

The eastern dog park is mostly mixed grassland (native grasses, non-native grasses, and weeds). The western leash-only area is largely dominated by nonnative grasses, particularly smooth brome, as well as large areas of the noxious weeds that coincide with the active prairie dog colony. Prairie dogs cause disturbance to the soil as they burrow and also because they prefer low vegetation which allows them to see predators. In urban environments, colonies often remain in the same location for years which leads to bare ground, allowing invasive annual plants to take root. This can lead to large areas of field bindweed, kochia, and curly dock near prairie dog colonies.

Smooth brome

Brone

Field bindweed typical in the active prairie dog areas

Bindweed

Mixed grasses: buffalo grass (native) in front, cheatgrass (noxious weed) behind, and smooth brome (invasive) in the rear of the photo

Mixed Grasses

Cheatgrass, a noxious weed

Cheatgrass

Smooth brome covers large areas of the western part of WHOS

Smooth Brone

Nonnative species can outcompete native plants and easily spread. Careful management practices are often necessary to control these species. Smooth brome is problematic due to its invasive nature and ability to quickly take over an area, creating a monoculture and decreasing biodiversity. A healthy ecosystem requires different types of plants to thrive.

Be your own detective! See if you can identify the different types of plants growing in the Westminster Hills and in the grasslands throughout your community. Native grasses have been replaced by nonnative and invasive plants in many of Westminster’s Open Spaces. However, native buffalo and blue grama grasses can still be found.

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Wildlife

The ERO assessment observed a wide variety of birds living in the Westminster Hills including the red-winged black bird, great blue heron, redhead duck, cattle egret, red-tailed hawk, Swainson's hawk, turkey vulture, killdeer, northern flicker, American crow, horned lark, brewer's blackbird, American kestrel, common yellowthroat, house finch, barn swallow, ruddy duck, American white pelican, double-crested cormorant, black-billed magpie, vesper sparrow, great-tailed grackle, common grackle, Say's phoebe, western meadowlark, European starling, American robin, yellow-headed blackbird, and mourning dove. The black tailed prairie dog and the cottontail rabbit were also observed.

ERO determined that the WHOS provides “high-quality nesting and foraging habitats for grassland bird, arboreal bird, ducks, and raptor species as well as reptiles, small and large mammals. The black-tailed prairie dog colonies found on the Property provide food and shelter for many other grassland species and can have a considerable effect on community structure and ecosystem function.”

Be your own detective! Listen for the meadowlarks and see how many different birds you can identify living in the off-leash area. Take a walk on the west side (but keep Fido on a leash!) and observe the prairie dog colonies, and the different types of animals living near the Mower Reservoir.

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I heard there are endangered species in WHOS?! Is that true?

Nope! Despite misinformation being spread, the ERO assessment did not find endangered species living at WHOS, nor is there suitable or historic habitat in the eastern off-leash dog area for all federal and state listed endangered species in Colorado, with the exception of the black footed ferret.

The burrowing owl is a threatened species in the state of Colorado, meaning the species is at risk to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The ERO assessment found evidence that the burrowing owl has historically nested in the northwestern portion of WHOS. However, the owls were not observed during the 2023 summer assessment. The burrowing owl migrates during the winter, returning to Colorado in the spring and summer months to breed.

Upon learning that the burrowing owl can sometimes chose part of WHOS as their summer home, the Guardians immediately suggested protecting the nesting grounds by restricting all dog access, considering seasonal closures if appropriate, and re-evaluating the wisdom of bike travel through this potentially sensitive area.

The black footed ferret is an endangered species and the focus of intensive conservation efforts to keep the species from disappearing entirely. The species relies on prairie dog colonies for food and shelter, and thus has been impacted by threats to prairie dog populations. It is unlikely that WHOS would make a suitable reintroduction site for the black footed ferret due to the proximity of metro Denver and heavy human recreation in nearby open spaces.

The riparian woodland and emergent marsh by the Mower Reservoir may have suitable habitat for additional sensitive species, such as the threatened Preble’s jumping mouse and the species of concern northern leopard frog. These species require habitat near water, which is not present in the off-leash dog area at WHOS (the irrigation ditch in the eastern dog park only intermittently flows when the Church and Dry Creek Valley Ditch Authorities are delivering water to their customers).

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What about E. coli?

The ERO evaluation of WHOS included soil sampling which did not detect E. coli in the soil. However, E. coli was detected in water samples at concentrations that exceed EPA’s threshold value in the Mower Reservoir and in the ditch. The Church Ditch/Dry Creek Valley ditch conveys irrigation water from Clear Creek in Golden, weaving up past Standley Lake, through the dog park, and ending in the Great Western Reservoir. On its way, it passes through many grazing pastures and leech fields, which contribute to the bacteria levels in the water. Samples were collected in two locations, as the water enters the park and as it exits the park. E. coli levels were not significantly different between the two sampling points, indicating the contamination likely occurs prior to the water entering WHOS. The sampling data indicates that dog waste is unlikely to be a significant contributing factor in contamination, but you can expect to see signs in the near future communicating the potential hazards of exposure. There is a lack of research to determine the level of colony forming units (CFU) which poses a risk to dogs, however some evidence suggests that dogs have a much greater tolerance to E. coli exposure than humans.

Regardless, always remember to clean up after your dog!

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What’s next?

Westminster City Council and PRL have been developing a new land management plan going forward. The Guardians have also submitted a proposed action plan to address concerns at WHOS, you can read it Here.

We will likely have to say goodbye to some of our favorite trails as selected social trails are closed for restoration to give wildlife more space. Expect to see the redesignation of trail boundaries, improved signage, and community clean up days as we work together to develop a long-term strategy for sustainable management of the land.

Decisions have yet to be made regarding the level of restoration efforts to restore the Westminster Hills back to the native shortgrass prairie. Restoration of native grasses will likely need to occur over the entire 1,027-acre property and could involve digging up all current vegetation to replant with native seeds. Drastic approaches such as this must be weighed with the impact to current wildlife living there, possibility of disturbing contaminated soil near Rocky Flats, effects of chemical control methods using various pesticides and herbicides, the impact of a changing climate and drought conditions on the ability of native plants to successfully reestablish, and finally the cost to taxpayers to accomplish this enormous goal.

We certainly have a lot of work to do going forward. The Guardians stand committed to working with the City to preserve this incredible land.

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